U.S. patent application number 17/597848 was filed with the patent office on 2022-09-08 for optical output control device and laser device having same.
The applicant listed for this patent is LUTRONIC CORPORATION. Invention is credited to Hee Chul Lee.
Application Number | 20220280234 17/597848 |
Document ID | / |
Family ID | 1000006418838 |
Filed Date | 2022-09-08 |
United States Patent
Application |
20220280234 |
Kind Code |
A1 |
Lee; Hee Chul |
September 8, 2022 |
OPTICAL OUTPUT CONTROL DEVICE AND LASER DEVICE HAVING SAME
Abstract
According to an embodiment of the present disclosure, an optical
output control device includes: a wavelength-selective reflector
configured to reflect light in a predetermined wavelength band and
incident at a reference angle .theta..sub.c; and a driving unit
configured to rotate the wavelength-selective reflector to adjust
an angle of incidence of light incident on the wavelength-selective
reflector.
Inventors: |
Lee; Hee Chul; (Goyang-si,
Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LUTRONIC CORPORATION |
Goyang-si, Gyeonggi-do |
|
KR |
|
|
Family ID: |
1000006418838 |
Appl. No.: |
17/597848 |
Filed: |
August 28, 2020 |
PCT Filed: |
August 28, 2020 |
PCT NO: |
PCT/KR2020/011539 |
371 Date: |
January 26, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2018/2283 20130101;
A61B 18/20 20130101; A61B 2018/00702 20130101 |
International
Class: |
A61B 18/20 20060101
A61B018/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2019 |
KR |
10-2019-0106639 |
Claims
1. An optical output control device comprising: a
wavelength-selective reflector configured to reflect light in a
predetermined wavelength band and incident at a reference angle
.theta..sub.c; and a driving unit configured to rotate the
wavelength-selective reflector to adjust an angle of incidence of
light incident on the wavelength-selective reflector.
2. The optical output control device of claim 1, further
comprising: a photodetector configured to sense an amount of light
reflected from the wavelength-selective reflector or passing
through the wavelength-selective reflector; and a processor
configured to generate, based on the amount of light sensed by the
photodetector, a control signal to be transmitted to the driving
unit.
3. The optical output control device of claim 2, wherein the
processor is further configured to predict an output value from the
amount of sensed light, and calculate a rotation angle for the
wavelength-selective reflector by comparing the predicted output
value with a set target value.
4. The optical output control device of claim 1, wherein the
wavelength-selective reflector comprises: a transparent member
having an entrance surface and an exit surface, which are opposite
each other; and a wavelength-selective coating layer formed on the
entrance surface to reflect light in the predetermined wavelength
band.
5. The optical output control device of claim 4, wherein an
anti-reflection coating layer is formed on the exit surface.
6. The optical output control device of claim 1, further comprising
an optical path adjuster arranged on a traveling path of light that
passed through the wavelength-selective reflector and configured to
be rotated for adjusting the traveling path.
7. The optical output control device of claim 6, wherein the
optical path adjuster is further configured to adjust the traveling
path of light that passed through the wavelength-selective
reflector to be aligned with a traveling path of the light when the
light is incident on the wavelength-selective reflector.
8. An optical device comprising the optical output control device
of claim 1.
9. A laser device comprising: a light source unit comprising a
laser medium, a first mirror and a second mirror which are arranged
with the laser medium therebetween, and an excitation light source
configured to supply light to the laser medium, the light source
unit being configured to generate light in a predetermined
wavelength band; a wavelength-selective reflector arranged on a
path of light output from the light source unit and configured to
reflect light in the predetermined wavelength band and incident at
a reference angle .theta..sub.c; a photodetector configured to
sense an amount of light reflected from the wavelength-selective
reflector or passing through the wavelength-selective reflector; a
driving unit configured to rotate the wavelength-selective
reflector to adjust an angle of incidence of light incident on the
wavelength-selective reflector; and a processor configured to
generate a control signal to be transmitted to the driving
unit.
10. The laser device of claim 9, wherein the wavelength-selective
reflector is arranged such that an incident angle .theta..sub.i at
which light generated from the light source unit is incident is
different from the reference angle .theta..sub.c.
11. The laser device of claim 9, wherein the processor is further
configured to generate the control signal based on the amount of
light sensed by the photodetector.
12. The laser device of claim 11, wherein the photodetector is
arranged to sense the amount of light reflected from the
wavelength-selective reflector.
13. The laser device of claim 12, wherein the processor is further
configured to predict an output value from the amount of reflected
light, and calculate a rotation angle for the wavelength-selective
reflector by comparing the predicted output value with a set target
value.
14. The laser device of claim 12, wherein the processor is further
configured to calculate a rotation angle for the
wavelength-selective reflector by comparing the amount of reflected
light with a set reference value.
15. The laser device of claim 9, wherein the wavelength-selective
reflector comprises: a transparent member having an entrance
surface and an exit surface, which are opposite each other; and a
wavelength-selective coating layer formed on the entrance surface
to reflect light in the predetermined wavelength band.
16. The laser device of claim 15, further comprising an optical
path adjuster arranged on a traveling path of light that passed
through the wavelength-selective reflector and configured to be
rotated for adjusting the traveling path.
17. The laser device of claim 16, wherein the optical path adjuster
is further configured to adjust the traveling path of light that
passed through the wavelength-selective reflector to be aligned
with a traveling path of the light when the light is incident on
the wavelength-selective reflector.
18. The laser device of claim 16, wherein the optical path adjuster
is arranged symmetrically to the wavelength-selective reflector
with respect to a plane perpendicular to the traveling path of
light that passed through the wavelength-selective reflector.
19. The laser device of claim 16, wherein the optical path adjuster
comprises a material having a refractive index equal to a
refractive index of the transparent member and has a thickness
equal to a thickness of the transparent member.
20. The laser device of claim 16, wherein the driving unit is
further configured to rotate the optical path adjuster in
conjunction with rotation of the wavelength-selective reflector
such that the optical path adjuster is rotated by a rotation angle
of the wavelength-selective reflector in a direction opposite to a
rotation direction of the wavelength-selective reflector.
Description
TECHNICAL FIELD
[0001] Embodiments of the present disclosure relate to an optical
output control device and a laser device including the optical
output control device.
BACKGROUND ART
[0002] Laser beams are used in various fields for industrial,
medical, and military purposes. In particular, medical lasers are
widely used in surgeries, internal medicine, ophthalmology,
dermatology, dentistry, and the like because they allow
concentration of a preset amount of energy at a local site and
enable non-invasive treatment.
[0003] Medical lasers are required to maintain a proper output
level for obtaining therapeutic effects.
DESCRIPTION OF EMBODIMENTS
Technical Problem
[0004] Provided are an optical output control device and a laser
device having a stable optical output level by using the optical
output control device.
Solution to Problem
[0005] According to an aspect, an optical output control device
includes: a wavelength-selective reflector configured to reflect
light in a predetermined wavelength band and incident at a
reference angle .theta..sub.c; and a driving unit configured to
rotate the wavelength-selective reflector to adjust an angle of
incidence of light incident on the wavelength-selective
reflector.
[0006] The optical output control device may further include: a
photodetector configured to sense an amount of light reflected from
the wavelength-selective reflector or passing through the
wavelength-selective reflector; and a processor configured to
generate, based on the amount of light sensed by the photodetector,
a control signal to be transmitted to the driving unit.
[0007] The processor may be further configured to predict an output
value from the amount of sensed light, and set a rotation angle for
the wavelength-selective reflector by comparing the predicted
output value with a set target value.
[0008] The wavelength-selective reflector may include: a
transparent member having an entrance surface and an exit surface,
which are opposite each other; and a wavelength-selective coating
layer formed on the entrance surface to reflect light in the
predetermined wavelength band.
[0009] An anti-reflection coating layer may be formed on the exit
surface.
[0010] The optical output control device may further include an
optical path adjuster arranged on a traveling path of light that
passed through the wavelength-selective reflector and configured to
be rotated for adjusting the traveling path.
[0011] The optical path adjuster may be further configured to
adjust the traveling path of light that passed through the
wavelength-selective reflector to be aligned with a traveling path
of the light when the light is incident on the wavelength-selective
reflector.
[0012] According to an aspect, a laser device includes: a light
source unit including a laser medium, a first mirror and a second
mirror which are arranged with the laser medium therebetween, and
an excitation light source configured to supply light to the laser
medium, the light source unit being configured to generate light in
a predetermined wavelength band; a wavelength-selective reflector
arranged on a path of light output from the light source unit and
configured to reflect light in the predetermined wavelength band
and incident at a reference angle .theta..sub.c; a photodetector
configured to sense an amount of light reflected from the
wavelength-selective reflector or passing through the
wavelength-selective reflector; a driving unit configured to rotate
the wavelength-selective reflector to adjust an angle of incidence
of light incident on the wavelength-selective reflector; and a
processor configured to generate a control signal to be transmitted
to the driving unit.
[0013] The wavelength-selective reflector may be arranged such that
an incident angle .theta..sub.i at which light generated from the
light source unit is incident may be different from the reference
angle .theta..sub.c.
[0014] The processor may be further configured to generate the
control signal based on the amount of light sensed by the
photodetector.
[0015] The photodetector may be arranged to sense the amount of
light reflected from the wavelength-selective reflector.
[0016] The processor may be further configured to predict an output
value from the amount of reflected light, and set a rotation angle
for the wavelength-selective reflector by comparing the predicted
output value with a set target value.
[0017] The processor may be further configured to set a rotation
angle for the wavelength-selective reflector by comparing the
amount of reflected light with a set reference value.
[0018] The wavelength-selective reflector may include: a
transparent member having an entrance surface and an exit surface,
which are opposite each other; and a wavelength-selective coating
layer formed on the entrance surface to reflect light in the
predetermined wavelength band.
[0019] The laser device may further include an optical path
adjuster arranged on a traveling path of light that passed through
the wavelength-selective reflector and configured to be rotated for
adjusting the traveling path.
[0020] The optical path adjuster may be further configured to
adjust the traveling path of light that passed through the
wavelength-selective reflector to be aligned with a traveling path
of the light when the light is incident on the wavelength-selective
reflector.
[0021] The optical path adjuster may be arranged symmetrically to
the wavelength-selective reflector with respect to a plane
perpendicular to the traveling path of light that passed through
the wavelength-selective reflector.
[0022] The optical path adjuster may include a material having a
refractive index equal to a refractive index of the transparent
member and may have a thickness equal to a thickness of the
transparent member.
[0023] The driving unit may be further configured to rotate the
optical path adjuster in conjunction with rotation of the
wavelength-selective reflector such that the optical path adjuster
may be rotated by a rotation angle of the wavelength-selective
reflector in a direction opposite to a rotation direction of the
wavelength-selective reflector.
Advantageous Effects of Disclosure
[0024] The optical output control device may control optical output
by using a total-reflection coating layer without using the
polarization characteristics of incident light.
[0025] The laser device including the optical output control device
may have uniform optical output regardless of the polarization
state of laser light.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a flowchart conceptually illustrating operations
of an optical output control device according to an embodiment.
[0027] FIG. 2 illustrates a schematic structure of an optical
output control device according to an embodiment.
[0028] FIGS. 3A and 3B illustrate a detailed structure of a
wavelength-selective reflector of the optical output control device
shown in FIG. 2 and an optical path along which the amount of light
transmission varies according to the angle of incidence of
light.
[0029] FIG. 4 is a graph illustrating an example in which the
amount of light transmission varies according to the angle of
incidence on the wavelength-selective reflector of the optical
output control device shown in FIG. 2.
[0030] FIG. 5 illustrates a schematic structure of an optical
output control device according to another embodiment.
[0031] FIG. 6 illustrates a schematic structure of an optical
output control device according to another example embodiment.
[0032] FIG. 7 illustrates a schematic structure of a laser device
according to an embodiment.
[0033] FIG. 8 is a flowchart conceptually illustrating operations
in which the laser device shown in FIG. 7 emits controlled output
light.
[0034] FIGS. 9 and 10 are example flowcharts illustrating more
detailed operations of controlling output light in the laser device
shown in FIG. 7.
MODE OF DISCLOSURE
[0035] The present disclosure may have various different forms and
various embodiments, and specific embodiments are illustrated in
the accompanying drawings and are described herein in detail.
Effects and features of the present disclosure, and methods of
achieving the effects and features will become apparent with
reference to the accompanying drawings and the embodiments
described below in detail. However, the present disclosure is not
limited to the embodiments described below and may be implemented
in various forms.
[0036] Hereinafter, the embodiments will be described with
reference to the accompanying drawings. In the drawings, like
reference numerals denote like elements, and overlapping
descriptions thereof will be omitted.
[0037] In the following descriptions of the embodiments, although
terms such as "first" and "second" are used to describe various
elements, these elements should not be limited by these terms.
These terms are only used to distinguish one element from another
element.
[0038] In the following descriptions of the embodiments, the terms
of a singular form may include plural forms unless referred to the
contrary.
[0039] In the following descriptions of the embodiments, the
meaning of "include," "comprise," "including," or "comprising"
specifies a property or an element, but does not exclude other
properties or elements.
[0040] In the descriptions of the embodiments, when a region or an
element is referred to as being "above" or "on" another region or
element, it can be directly on the other region or element, or
intervening regions or elements may also be present.
[0041] In the drawings, the sizes of elements may be exaggerated
for clarity. For example, in the drawings, the size or thickness of
each element may be arbitrarily shown for illustrative purposes,
and thus the present disclosure should not be construed as being
limited thereto.
[0042] The order of processes explained in one embodiment may be
changed in a modification of the embodiment or another embodiment.
For example, two processes sequentially explained may be performed
substantially at the same time or in the reverse of the explained
order.
[0043] In the descriptions of the embodiments, when a region, an
element, or the like is referred to as being "connected to,"
another region or element, it may be directly connected to the
other region or element or may be indirectly connected to the other
region or element through intervening regions or elements.
[0044] FIG. 1 is a flowchart conceptually illustrating operations
of adjusting optical output in an optical output control device
according to an embodiment.
[0045] A wavelength-selective reflector is an optical member
configured to reflect light in a predetermined wavelength band and
incident at a predetermined reference angle .theta..sub.c. When
light is incident on the wavelength-selective reflector (S10), a
portion of the light satisfying reflection conditions is reflected,
and the remaining portion of the light passes through the
wavelength-selective reflector (S20).
[0046] In this manner, the amount of reflected light and the amount
of transmitted light vary depending on the angle of incidence on
the wavelength-selective reflector. Because the angle of incidence
of light on the wavelength-selective reflector is determined by the
arrangement angle of the wavelength-selective reflector with
respect to the incident light, the amount of light transmission
through the wavelength-selective reflector may be adjusted by
sensing the amount of light reflected by the wavelength-selective
reflector (S30) and adjusting the arrangement angle of the
wavelength-selective reflector according to the sensed amount of
light (S40). In addition, if necessary, the path of transmitted
light may be additionally adjusted (S50). Through these operations,
light may be obtained with desired optical output level.
[0047] In the drawing, an example is illustrated in which, for
output adjustment, light reflected by the wavelength-selective
reflector is sensed, and the arrangement angle of the
wavelength-selective reflector is adjusted by using results of the
sensing. However, this is a non-limiting example. For example, it
is also possible to sense light passing through the
wavelength-selective reflector and adjust the arrangement angle of
the wavelength-selective reflector by using results of the
sensing.
[0048] The above-described concept may be implemented in various
devices, and implemented example structures will now be
described.
[0049] FIG. 2 illustrates a schematic structure of an optical
output control device according to an embodiment. FIGS. 3A and 3B
are views illustrating a detailed structure of a
wavelength-selective reflector of the optical output control device
shown in FIG. 2 and an optical path in which the amount of light
transmission varies according to the angle of incidence of light.
FIG. 4 is a graph illustrating an example in which the amount of
light transmission varies according to the angle of incidence on
the wavelength-selective reflector of the optical output control
device shown in FIG. 2.
[0050] Referring to FIG. 2, an optical output control device 1000
includes: a wavelength-selective reflector 100 arranged such that a
first light beam L1 is incident on the wavelength-selective
reflector 100 at an incident angle .theta..sub.i; and a driving
unit 300 configured to rotate the wavelength-selective reflector
100 to adjust the incident angle .theta..sub.i of light incident on
the wavelength-selective reflector 100.
[0051] The optical output control device 1000 may further include:
a photodetector 200 configured to sense the amount of light that
passed through the wavelength-selective reflector 100; and a
processor 400 configured to generate a control signal to be
transmitted to the driving unit 300 based on the amount of light
sensed by the photodetector 200.
[0052] The wavelength-selective reflector 100 is configured to
reflect light in a predetermined wavelength band and incident at a
set reference angle .theta..sub.c.
[0053] As shown in FIGS. 3A and 3B, the wavelength-selective
reflector 100 includes: a transparent member 110 having an entrance
surface 110b and an exit surface 110a which are opposite each
other; and a wavelength-selective coating layer 120 formed on the
entrance surface 110b and reflecting light in the predetermined
wavelength band. In addition, an anti-reflection coating layer (not
shown) may be formed on the exit surface 110a.
[0054] The wavelength-selective coating layer 120 may include a
plurality of material layers having different optical properties.
Incident light satisfying predetermined conditions may be totally
reflected as a result of interaction between the incident light and
the plurality of material layers. For example, light incident on an
interface between media having different refractive indexes is
reflected and transmitted while being refracted, and the total
amount of reflected light and the total amount of transmitted light
are determined by interference between the reflected light and the
transmitted light which travel along a plurality of paths formed by
a plurality of interfaces. Considering this interference, the
refractive index and the thickness of each layer may be determined
such that light satisfying specific incident angle conditions may
be totally reflected. In addition, based on that optical properties
depend on the wavelength of incident light, specific properties of
the plurality of material layers of the wavelength-selective
coating layer 120 may be set such that the wavelength-selective
coating layer 120 may total reflect light having the predetermined
wavelength band and incident at the set reference angle
.theta..sub.c. The wavelength-selective coating layer 120, which is
set as described above, reflects only a portion of light and
transmits the other portion of the light, among light incident at
an incident angle different from the set reference angle
.theta..sub.c.
[0055] Referring to FIG. 3A, when a first light beam L1 having the
predetermined wavelength band is incident on the
wavelength-selective reflector 100 at the reference angle
.theta..sub.c, all the incident first light beam L1 is reflected.
That is, the amount of a second light beam L2, which is a reflected
light beam, is equal to the amount of the first light beam L1.
[0056] As shown in FIG. 3B, when a first light beam L1 is incident
on the wavelength-selective reflector 100 at an incident angle
.theta..sub.i different from the reference angle .theta..sub.c, a
portion of the light is reflected, and the other portion of the
light is transmitted. That is, the path of the first light beam L1
is divided into two paths: a path of a second light beam L2 which
is a reflected light beam; and a path of to third light beam L3
which is a transmitted light beam. The amount of the third light
beam L3 may vary according to the difference between the incident
angle .theta..sub.i and the reference angle .theta..sub.c.
[0057] In addition, due to the thickness (t) and the refractive
index (n) of the transparent member 110, the direction of the third
light beam L3 is different from the traveling direction in which
the first light beam L1 is incident on the wavelength-selective
reflector 100. The first light beam L1 is transmitted while being
refracted at the entrance surface 110b and the exit surface 110a of
the transparent member 110, and then travels along a path shifted
by a distance (d) from the original traveling path thereof. As
illustrated, when the entrance surface 110b and the exit surface
110a are parallel to each other, the traveling path of light is
moved in parallel by the distance (d). However, this is a
non-limiting example. For example, the entrance surface 110b and
the exit surface 110a may not be parallel to each other, and in
this case, the new path may not be parallel to the original path. A
path change caused by the wavelength-selective reflector 100 may be
adjusted by using an additional path-adjustment optical member, and
this will be described later in other embodiments.
[0058] As illustrated in FIG. 4, the amount of transmitted light
increases as .DELTA..theta. defined by
|.theta..sub.i-.theta..sub.c| increases. The illustrated graph is
an example, and the graph may be a straight line or another
non-linear curve. The shape of the graph may vary depending on the
detailed properties of the wavelength-selective coating layer 120
formed on the wavelength-selective reflector 100.
[0059] According to the properties of the wavelength-selective
reflector 100, desired output may be obtained from the
wavelength-selective reflector 100 by sensing the amount of light
traveling via the wavelength-selective reflector 100 and adjusting
the arrangement angle of the wavelength-selective reflector 100. To
this end, the photodetector 200 may be used to sense light
traveling via the wavelength-selective reflector 100, that is, to
sense light reflected by or passing through the
wavelength-selective reflector 100.
[0060] In FIG. 2, the photodetector 200 is arranged on a path of
light reflected by the wavelength-selective reflector 100, that is,
the photodetector 200 may sense the amount of light reflected by
the wavelength-selective reflector 100.
[0061] The processor 400 may set the rotation angle of the
wavelength-selective reflector 100 based on the amount of light
sensed by the photodetector 200. For example, the processor 400 may
predict an output value of the wavelength-selective reflector 100
from the amount of light sensed by the photodetector 200. That is,
the processor 400 may predict the amount of a third light beam L3
passing through the wavelength-selective reflector 100. Then, the
processor 400 may calculate a rotation angle for the
wavelength-selective reflector 100 by comparing the predicted
output value with a set target value.
[0062] The driving unit 300 may rotate the wavelength-selective
reflector 100 under the control of the processor 400. The axis of
rotation, on which the wavelength-selective reflector 100 is
rotated, is perpendicular to a plane determined by the path of a
first light beam L1 which is incident light, the optical path of a
second light beam L2 which is reflected light, and the path of a
third light beam L3 which is transmitted light, and according to
the rotation of the wavelength-selective reflector 100 on the axis
of rotation, the incident angle .theta..sub.i of the first light
beam L1 incident on the wavelength-selective reflector 100 is
varied. A variation in the incident angle .theta..sub.i results in
a variation in the amount of transmitted light L3. That is, desired
output may be obtained by appropriately adjusting the rotation
angle of the wavelength-selective reflector 100.
[0063] The optical output control method described above is
different from optical output control methods of the related art
which use a specific polarized state of light. In optical output
control methods of the related art, input light is polarized light,
and thus, there may be spatial regions having slightly different
polarization components. In this case, the distribution of an
output-controlled beam is not uniform.
[0064] The optical output control device of the embodiment may be
used regardless of the polarization state of light, and thus has
substantially no problem regarding non-uniformity of
output-controlled light.
[0065] Hereinafter, examples of optical output devices will be
described according to various embodiments.
[0066] FIG. 5 illustrates a schematic structure of an optical
output control device according to another embodiment.
[0067] An optical output control device 1100 of the current
embodiment is different from the optical output control device 1000
shown in FIG. 2 in that a dumper 510 is arranged on the path of a
second light beam L2 reflected by a wavelength-selective reflector
100, and a photodetector 200 is arranged at a different
position.
[0068] The dumper 510 may be arranged on a reflection path of the
wavelength-selective reflector 100 to simply process a reflected
light beam, and the photodetector 200 may be arranged to detect the
amount of light branching off from a third light beam L3 that has
passed through the wavelength-selective reflector 100. To this end,
a half mirror 530 may be arranged on a path of the third light beam
L3 that passed through the wavelength-selective reflector 100. The
half mirror 530 is a member configured to transmit half of incident
light and reflect the rest of the incident light. The output value
of a fourth light beam L4 passing through the half mirror 530 may
be predicted by detecting the amount of a fifth light beam L5
reflected by the half mirror 530. Based on this, the
wavelength-selective reflector 100 may be rotated to increase or
decrease the output value to a desired value, thereby obtaining a
desired output value. In the description of the current embodiment,
the arrangement of the half mirror 530 is an example, and another
type of beam splitter configured to split light may be used instead
of the half mirror 530.
[0069] In the following embodiments, the photodetector 200 is
illustrated as being arranged on a path of light reflected from the
wavelength-selective reflector 100, but embodiments are not limited
thereto. That is, the following embodiments may be modified like
the current embodiment such that the photodetector 200 may be
arranged on a path of light that passed through the
wavelength-selective reflector 100.
[0070] FIG. 6 illustrates a schematic structure of an optical
output control device according to another example embodiment.
[0071] An optical output control device 1200 according to the
present embodiment is different from the optical output control
device 1000 shown in FIG. 2, in that the optical output control
device 1200 further includes an optical path adjuster 600 arranged
on a path of light passing through a wavelength-selective reflector
100.
[0072] As described with reference to FIG. 3B, the path of a third
light beam L3 that has passed through the wavelength-selective
reflector 100 may be shifted by a distance (d) from the path of a
first light beam L1 which is an incident light beam. The optical
path adjuster 600 may be rotated to adjust the path of light that
passed through the wavelength-selective reflector 100 to be aligned
with the path of light incident on the wavelength-selective
reflector 100.
[0073] Based on the amount of light sensed by a photodetector 200,
a processor 400 may generate a driving signal for rotating the
wavelength-selective reflector 100 and also a driving signal for
rotating the optical path adjuster 600.
[0074] A driving unit 350 may be configured to independently drive
the wavelength-selective reflector 100 and the optical path
adjuster 600. The optical path adjuster 600 may be driven to rotate
to correct a deviation of the path of light which is caused by the
wavelength-selective reflector 100, or in addition to this, the
optical path adjuster 600 may be driven to rotate so that another
path change is possible. In this case, a driving force independent
of rotation of the wavelength-selective reflector 100 may be
transmitted to the optical path adjuster 600.
[0075] Alternatively, the driving unit 350 may include, for
example, a driving force transmitting unit such as a gear
configured to transmit a driving force generated from a single
driving source to both the wavelength-selective reflector 100 and
the optical path adjuster 600. The driving force transmitting unit
may be specifically set to transmit a driving force to the optical
path adjuster 600 for correcting an optical path deviation caused
by the rotation of the wavelength-selective reflector 100. For
example, a driving force generated from the single driving source
may be transmitted to the wavelength-selective reflector 100 and
the optical path adjuster 600 according to a predetermined
relationship.
[0076] As shown in the drawing, the optical path adjuster 600 may
be arranged symmetrically to the wavelength-selective reflector 100
with respect to a plane which is perpendicular to the traveling
path of light passing through the wavelength-selective reflector
100. In addition, the optical path adjuster 600 may include a
material having the same refractive index as that of a transparent
member of the wavelength-selective reflector 100 and may have the
same thickness as the transparent member. An anti-reflection
coating layer (not shown) may be formed on an entrance surface
and/or an exit surface of the light path controller 600.
[0077] When the optical path adjuster 600 includes a material
having the same refractive index as that of the transparent member
of the wavelength-selective reflector 100 and has the same
thickness of the wavelength-selective reflector 100, an optical
path deviation caused by the wavelength-selective reflector 100 may
be corrected by rotating the optical path adjuster 600 by the same
angle as the wavelength-selective reflector 100 in the opposite
direction to the direction in which the wavelength-selective
reflector 100 is rotated. However, this is a non-limiting example,
and the optical path adjuster 600 may have another thickness and
another refractive index. In this case, the optical path adjuster
600 may be rotated to a different angle to correct an optical path
deviation.
[0078] The driving unit 350 may be configured to drive the optical
path adjuster 600 according to the rotation of the
wavelength-selective reflector 100 such that the optical path
adjuster 600 may be rotated the same angle as the
wavelength-selective reflector 100 in the opposite direction to the
direction in which the wavelength-selective reflector 100 is
rotated. For example, the driving force transmitting unit may be
configured such that a driving force generated from the single
driving source may be transmitted to both the wavelength-selective
reflector 100 and the optical path adjuster 600 with the same
magnitude but in opposite directions.
[0079] The optical output devices 1000, 1100, and 1200 described
above may be applied to various optical devices requiring output
control.
[0080] FIG. 7 is a view illustrating a schematic structure of a
laser device according to an embodiment.
[0081] A laser device 1400 includes: a light source unit 700
configured to generate and output laser light in a predetermined
wavelength band; a wavelength-selective reflector 100 arranged on a
path of light emitted from the light source unit 700 and configured
to reflect light having the predetermined wavelength band and
incident at a reference angle .theta..sub.c; a photodetector 200
configured to sense the amount of light passing through the
wavelength-selective reflector 100; a driving unit 350 configured
to rotate the wavelength-selective reflector 100 for adjusting the
angle of incidence of light incident on the wavelength-selective
reflector 100; and a processor 450 configured to generate a control
signal to be transmitted to the driving unit 350.
[0082] The light source unit 700 may include a laser medium 740, an
excitation light source 710 configured to supply light to the laser
medium 740, and a first mirror 730 and a second mirror 750 which
are arranged with the laser medium 740 therebetween. The first
mirror 730, the laser medium 740, and the second mirror 750
constitute a laser oscillation unit 770 in which light from the
excitation light source 710 oscillates to produce laser light.
[0083] The excitation light source 710, which may be a flash lamp,
emits light by receiving power from a power supply (not shown) and
provides the light to the laser medium 740. The excitation light
source 710 is not limited to a flash lamp and may include a laser
diode.
[0084] The laser medium 740 absorbs the energy of light supplied
from the excitation light source 710 and emits amplified light. The
laser medium 740 may be neodymium-doped yttrium aluminum garnet
(Nd:Yag). However, the laser medium 740 is not limited thereto, and
Er:Yag may be used as the laser medium 135.
[0085] The first mirror 730 and the second mirror 750 may be
arranged facing each other with the laser medium 740 therebetween
to form a resonance path of light amplified by the laser medium
740. The reflectivity of the first and second mirrors 730 and 750
may be set such that the first mirror 730 may function as a
reflection mirror, and the second mirror 750 may function as an
output mirror.
[0086] The elements and arrangement of the light source unit 700
are described as an example of a basic structure for generating
laser light. That is, the light source unit may include additional
optical elements for controlling the properties of laser light to
be emitted, and the arrangement of optical elements of the light
source unit 700 may be modified.
[0087] A first light beam L1, which is laser light generated from
the light source unit 700, may be in a specific polarization state
or a non-polarized state. Because the laser device 1400 of the
embodiment is capable of adjusting optical output regardless of the
polarization state of light, the laser device 1400 does not require
additional optical elements such as a polarizer or a phase
retarder, which are used in laser devices of the related art to
polarize light for optical output control.
[0088] The wavelength-selective reflector 100 may totally reflect a
first laser beam L1 generated from the light source unit 700 in a
predetermined wavelength band when the first laser beam L1 is
incident on the wavelength-selective reflector 100 at the reference
angle .theta..sub.c. The wavelength-selective reflector 100 may be
specifically configured as illustrated in FIGS. 3A and 3B, and a
wavelength-selective coating layer provided on the
wavelength-selective reflector 100 may be set to match the
wavelength band of light generated from the light source unit
700.
[0089] For example, the light source unit 700 may generate light in
a wavelength of about 1064 nm, and the wavelength-selective
reflector 100 may have a wavelength-selective coating layer that
totally reflects light in a wavelength of 1064 nm and incident at
an incident angle of 45 degrees. However, this is merely a
non-limiting example.
[0090] The wavelength-selective reflector 100 may be oriented such
that the incident angle .theta..sub.i of a first light beam L1
generated from the light source unit 700 is different from the
reference angle .theta..sub.c. In this case, the first light beam
L1 is split into a second light beam L2 as being reflected by the
wavelength-selective reflector 100 and a third light beam L3 as
being transmitted through the wavelength-selective reflector
100.
[0091] The photodetector 200 may be arranged on a path of the
second light beam L2 to sense the amount of light reflected by the
wavelength-selective reflector 100.
[0092] The processor 450 generates a control signal to be
transmitted to the driver 350 based on the amount of light sensed
by the photodetector 200. The processor 400 may also control the
overall operation of the laser device 1400 including the driving of
the excitation light source 710.
[0093] The laser device 1400 may further include an optical path
adjuster 600 arranged on a traveling path of the third light beam
L3 transmitted through the wavelength-selective reflector 100, and
the optical path adjuster 600 is configured to be rotated for
controlling the traveling path.
[0094] The optical path adjuster 600 adjusts the traveling path of
the first light beam L1 coming from the light source unit 700 such
that the traveling path of the first light beam L1 after the first
light beam L1 passes through the wavelength-selective reflector 100
may be aligned with the traveling path of the first light beam L1
incident on the wavelength-selective reflector 100.
[0095] The optical path adjuster 600 may be arranged symmetrically
to the wavelength-selective reflector 100 with respect to a plane
perpendicular to the traveling path of light that passed through
the wavelength-selective reflector 100. In addition, the optical
path adjuster 600 may include a material having the same refractive
index as that of a transparent member of the wavelength-selective
reflector 100 and may have the same thickness as the transparent
member.
[0096] The driving unit 350 may drive the optical path adjuster 600
according to the rotation of the wavelength-selective reflector 100
such that the optical path adjuster 600 may be rotated the same
angle as the wavelength-selective reflector 100 in the opposite
direction to the rotation direction of the wavelength-selective
reflector 100.
[0097] FIG. 8 is a flowchart conceptually illustrating operations
in which the laser device shown in FIG. 7 emits controlled output
light, and FIGS. 9 and 10 are example flowcharts exemplarily
illustrating more detailed operations of controlling output light
in the laser device shown in FIG. 7.
[0098] Referring to FIG. 8, the wavelength-selective reflector 100
is arranged such that the incident angle of light may be
.theta..sub.i (S100). In this case, the incident angle
.theta..sub.i may be different from the reference angle
.theta..sub.c. Light incident on the wavelength-selective reflector
100 is transmitted and reflected, and the reflected light or
transmitted light is sensed by the photodetector 200 (S200). Next,
a driving signal to be transmitted to the driving unit 350 is
generated based on the amount of sensed light (S300). The
wavelength-selective reflector 100 is driven according to the
driving signal such that the incident angle .theta..sub.i may be
changed or maintained (S400). In addition, the optical path
adjuster 600 is driven in conjunction with the driving of the
wavelength-selective reflector 200 (S500).
[0099] As illustrated in FIG. 9, an operation in which the
processor 450 generates a driving signal may be performed based on
a target value to be output. The photodetector 200 may sense the
amount of light reflected from the wavelength-selective reflector
100 (S320), and the processor 450 may predict an output value
P.sub.a from the sensed amount of reflected light (S340). Next, the
predicted output value P.sub.a is compared with a set target value
Pt (S360), and the rotation angle of the wavelength-selective
reflector 100 is set according to results of the comparison.
[0100] When results of the comparison between the output value
P.sub.a and the target value Pt shows that the output value P.sub.a
is greater than the target value Pt, the wavelength-selective
reflector is rotated in a direction for obtaining a lower output
value (S410). That is, the processor 450 generates a driving signal
for rotating the wavelength-selective reflector 100 in a direction
decreasing the difference .DELTA..theta. between the reference
angle .theta..sub.c and the incident angle .theta..sub.i at which
light is incident on the wavelength-selective reflector 100, and
the driving unit 350 rotates the wavelength-selective reflector 100
according to the driving signal.
[0101] When the output value P.sub.a is less than the target value
Pt, the wavelength-selective reflector 100 is rotated in a
direction for obtaining a higher output value (S430). That is, the
processor 450 generates a driving signal for rotating the
wavelength-selective reflector 100 in a direction increasing the
difference .DELTA..theta. between the reference angle .theta..sub.c
and the incident angle .theta..sub.i at which light is incident on
the wavelength-selective reflector 100, and the driving unit 350
rotates the wavelength-selective reflector 100 according to the
driving signal.
[0102] When the output value P.sub.a is equal to the target value
Pt, the arrangement angle of the wavelength-selective reflector 100
is maintained (S420). That is, because the difference
.DELTA..theta. in the current state corresponds to the target value
Pt, the wavelength-selective reflector 100 is not rotated to
maintain the incident angle .theta..sub.i corresponding to the
difference .DELTA..theta..
[0103] Alternatively, as illustrated in FIG. 10, the operation in
which the processor 450 generates a driving signal may be performed
by setting a reference value and comparing the reference value with
the amount of light reflected by the wavelength-selective reflector
100 to obtain a target output value.
[0104] The photodetector 200 senses the amount of light reflected
from the wavelength-selective reflector 100 (S320), and the
processor 450 compares the sensed amount of reflected light with a
set reference value R.sub.c (S370). Then, a rotation angle is set
for the wavelength-selective reflector 100 according to results of
the comparison.
[0105] When the amount R of reflected light sensed by the
photodetector 200 is less than the set reference value R.sub.c, the
wavelength-selective reflector 100 is rotated in a direction
increasing the amount of reflected light. That is, the processor
450 generates a driving signal for rotating the
wavelength-selective reflector 100 in a direction decreasing the
difference .DELTA..theta. between the reference angle .theta..sub.c
and the incident angle .theta..sub.i at which light is incident on
the wavelength-selective reflector 100, and the driving unit 350
rotates the wavelength-selective reflector 100 according to the
driving signal (S440).
[0106] When the amount R of reflected light sensed by the
photodetector 200 is greater than the set reference value R.sub.c,
the wavelength-selective reflector 100 is rotated in a direction
decreasing the amount of reflected light. The processor 450
generates a driving signal for rotating the wavelength-selective
reflector 100 in a direction increasing the difference
.DELTA..theta. between the reference angle .theta..sub.c and the
incident angle .theta..sub.i at which light is incident on the
wavelength-selective reflector 100, and the driving unit 350
rotates the wavelength-selective reflector 100 according to the
driving signal (S460).
[0107] When the amount R of reflected light sensed by the
photodetector 200 is equal to the set reference value R.sub.c, the
arrangement angle of the wavelength-selective reflector 100 is
maintained (S450). Because the difference .DELTA..theta. in the
current state corresponds to the target value Pt, the
wavelength-selective reflector 100 is not rotated to maintain the
incident angle .theta..sub.i corresponding to the difference
.DELTA..theta..
[0108] According to the configuration and operations described
above, the laser device 1400 of the embodiment may adjust its
output and maintain a uniform output distribution regardless of the
polarization state of laser light generated from the light source
unit 700.
[0109] Various embodiments of the present disclosure have been
described in detail, and those of ordinary skill in the art to
which the present disclosure pertains may make various
modifications therein without departing from the spirit and scope
of the present disclosure as defined by the appended claims.
Therefore, such modifications should be construed as being included
within the scope of the present disclosure.
* * * * *